The subject matter described herein relates generally to wind turbines and, more particularly, to a method and apparatus for powering a pitch control system of a wind turbine.
In at least one known wind turbine, a control system pitches one or more blades to adjust an operation of the wind turbine. The pitch control system includes a motor that rotatably drives the blades to a desired pitch angle to adjust an amount of wind energy captured by the blades. Known pitch control systems typically use a direct current (DC) motor that has a series field winding to pitch the blades. Such DC motors may include a dynamic braking resistor to facilitate absorbing excess energy generated by the DC motor during motor braking conditions. Moreover, to reverse a rotational direction of the DC motor, a plurality of rectification diodes are included in the pitch control system. Such dynamic braking resistors and rectification diodes may add cost and complexity to known pitch control systems, and may produce energy losses within the pitch control systems.
Moreover, in at least one known wind turbine, the series field winding of the DC motor shares a current with an armature of the DC motor. The current may be increased or decreased to adjust an operation of the DC motor. However, due to the common current between the armature and the winding, an adjustment of the armature current will also affect the winding current. As such, independent control of the armature and the winding of the DC motor may not be possible.